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Biomedical subjects

A Valerio

Publications and source records attributed to A Valerio.

At least 55 records · Page 3Linked to original sources
PubMed1996

Cirrhosis and pregnancy. A case report and review of the literature.

A clinical case of a pregnant suffering from hepatic cirrhosis with ascites, splenomegaly and portal hypertension is described. The pregnancy carried on till the 31st week, even though with the repeated use of tocholytic agents. Cesarean section was performed because of the onset of serious jaundice and the decline of general maternal conditions. The infant, who had an Apgar score of 8 at the 1st and 5th minute, died on the 10th day because of accuse haemorrhagic interstitial pneumonitis in premature lungs and hepatopathy associated with widespread jaundice. The mother was discharged on the 25th day of the postpartum period, in light of the net improvement of her general metabolic condition, the sudden regression of the jaundice and the decrease of the cholestasis indices. A review of the literature discussing maternal complications fetal risks, management of pregnancy and delivery and outcome of the newborn are presented.

Adult↗
PubMed1995

Differential expression of fetal and mature tau isoforms in primary cultures of rat cerebellar granule cells during differentiation in vitro.

The molecular mechanism(s) responsible for the differential expression of various tau protein isoforms as well as their functional role in morphogenesis, neurofibrillary tangle formation and neurodegeneration have not been completely clarified. We found that the expression of tau proteins in primary cultures of cerebellar granule cells from neonatal rat brain is a developmentally regulated process affecting tau synthesis at different levels. Changes in tau RNA splicing are clearly demonstrated by PCR data showing the switching on of the mRNA containing four internal repeats by DIV 6 and the switching off of the mRNA containing three internal repeats after DIV 12. The changes in mRNA levels of the different tau isoforms during development in vitro occur in parallel with changes in tau protein expression, both qualitatively and quantitatively, as shown by Western analysis of protein extracts from granule cells at different DIV with an anti-tau polyclonal antibody. Finally, as indicated by MAP2 and tau immunocytochemistry data, the switch in tau protein expression appears to be contemporary with neurite outgrowth and cell differentiation. Our data suggest that a differential expression of various tau proteins parallels the degree of cell maturation.

Animals↗
PubMed1995

Identification and characterization of a kappa B/Rel binding site in the regulatory region of the amyloid precursor protein gene.

Several observations support the hypothesis that pathogenetic mechanisms of beta amyloid formation in Alzheimer's disease may involve alterations in amyloid precursor protein (APP) gene expression. In this regard, molecular dissection of the APP gene transcriptional regulation is of primary importance. We report evidence that members of the family of transcription factors NF kappa B/Rel can specifically recognize two identical sequences located in the 5'-regulatory region of APP. These sequences, which we refer to as APP kappa B sites, interact preferentially with p50-containing members of the family. In particular, p50 homodimers and p50/p65 and p50/c-Rel heterodimers act as transcriptional activators at the APP kappa B site. Finally, the nuclear complex specifically binding to the APP kappa B sites proves to be an integral part of neurons and lymphocytes.

Alzheimer Disease↗
PubMed1995

Inhibition of glutamate-induced neurotoxicity by a tau antisense oligonucleotide in primary culture of rat cerebellar granule cells.

Short-term exposure of primary cultures of cerebellar granule cells from neonatal rat brain to high concentrations of glutamate resulted in a significant increase of both immunoreactivity to and mRNA levels of tau protein. Time-course experiments revealed the increases of tau immunoreactivity and mRNA levels to be maximal 2 h after the glutamate pulse. To investigate the relationship between newly synthesized tau protein and glutamate-induced neurotoxicity, neurons were preincubated with a specific tau antisense oligonucleotide. This treatment resulted in (i) inhibition of the glutamate-induced increase of tau immunoreactivity and (ii) a decrease in the sensitivity of the neurons to neurotoxic concentrations of glutamate. These data indicate that induction of the cytoskeleton-associated tau protein participates in the cascade of events promoted by glutamate leading to neurodegeneration.

Animals↗
PubMed1995

Opposing regulation of amyloid precursor protein by ionotropic and metabotropic glutamate receptors.

The effects of the ionotropic glutamate receptor (iGluR) selective agonist N-methyl-D-aspartate (NMDA) on amyloid precursor protein (APP) levels were investigated in primary cultures of rat cerebellar granule cells. Both immunocytochemistry and immunoblotting techniques showed increased APP levels 4 h after a 15 min pulse with NMDA. This effect was completely prevented by incubating the neurones in the presence of the selective metabotropic GluR (mGluR) agonist 1S,3R-ACPD. This phenomenon was related, in terms of doses and time, with the observed 1S,3R-ACPD-mediated protection on NMDA-induced granule cell death. Our findings indicate that APP metabolism is differentially regulated by the stimulation of various GluR subtypes. The GluR-mediated changes in APP content might participate in the control of neuronal viability.

Amyloid beta-Protein Precursor↗
PubMed1995

Tau protein immunolocalization in fetal and adult human spinal cord.

In the present study, the monoclonal antibody Alz-50 has been used to determine and compare the immunohistochemical localization of phosphorylated tau proteins in the developing and normal adult spinal cord. At all stages of fetal life Alz-50 fiber immunoreactivity was observed in the dorsal roots, in the dorsal and dorsolateral funiculi, and in restricted regions of the dorsal horn. Alz-50 immunoreactivity was also demonstrated in the dorsal root ganglion neurons. In the adult spinal cord a consistent pattern of Alz-50 fiber immunoreactivity was localized in the superficial layers of the dorsal horn (lamina I and II) but not in dorsal and dorsolateral funiculi and in the dorsal root ganglion. Comparable results in fetal specimens have been obtained employing PHF-1, a monoclonal antibody generated against paired helical filament proteins from Alzheimer brains, while no significant immunostaining for PHF-1 was observed in the adult spinal cord. In addition, the staining with monoclonal and polyclonal anti-tau antibodies overlapped with that of Alz-50. The transient, selective pattern of Alz-50 and PHF-1 immunoreactivity may disclose some relevant functions of tau proteins during somatosensory pathway development.

Adult↗
PubMed1994

Antisense strategy unravels tau proteins as molecular risk factors for glutamate-induced neurodegeneration.

1. We investigated the possible involvement of tau proteins in the neurotoxic process activated by glutamate using the oligonucleotide antisense strategy. 2. We found that pretreatment of granule cells with an antisense oligonucleotide of the tau gene completely prevented the increase in tau immunoreactivity induced by glutamate. 3. A significant amount of the tau antisense oligonucleotide (about 1 to 2% of total) was taken up by the cells and remained stable in the cells for at least 60 min. A dose-response study revealed that 25 microM tau antisense oligonucleotide was the most efficacious concentration in terms of prevention of glutamate-induced tau immunoreactivity increases, without affecting basal tau expression. Higher concentrations of tau oligonucleotide antisense reduced tau immunoreactivity in control cells. 4. Significantly, the concentration-response curve of glutamate for inducing neuronal death in cells pretreated with tau antisense oligonucleotide showed a shift to the right compared to those obtained in untreated or tau sense oligonucleotide-treated cells. 5. Since inhibition of tau synthesis does not completely prevent but only decreases the neuronal sensitivity to glutamate, it is tempting to speculate that accumulation of tau within the neuron in response to glutamate represents one of the molecular risk factors lowering the safety margin of neurons to excitotoxic-induced injury.

Animals↗
PubMed1994

Antisense strategy unravels a dopamine receptor distinct from the D2 subtype, uncoupled with adenylyl cyclase, inhibiting prolactin release from rat pituitary cells.

The antisense strategy was used to unravel the functional contribution of the mRNAs encoding dopamine (DA) receptors to the multiple transduction mechanisms operated by DA in rat pituitary cells. An antisense oligonucleotide was designed to recognize seven nucleotides upstream and 11 nucleotides downstream from the initiation translation codon of the mRNA that encodes the DA D2 receptor. Addition of the antisense oligonucleotide for 7 days to primary culture of rat pituitary cells resulted in a decreased expression of DA D2 receptor as shown by (a) the virtual disappearance of [3H]spiroperidol binding sites and (b) the marked reduction in the levels of both the long and the short splice variant of the D2 receptor mRNAs. After this treatment, the DA D2 receptor agonist bromocriptine lost its capability both to inhibit adenylyl cyclase activity and to reduce prolactin mRNA levels. On the contrary, the inhibition of prolactin release induced by bromocriptine was affected minimally by the antisense oligonucleotide treatment. These data indicate that (a) translation of the mRNA encoding DA D2 receptors results in receptors that are negatively coupled with adenylyl cyclase and functionally linked to inhibition of prolactin synthesis; and (b) the release of prolactin might be regulated, at least in part, by a DA receptor that is encoded by mRNA species distinct from those encoding the D2 receptor.

Adenylyl Cyclase Inhibitors↗
PubMed1994

Improvement of basal hepatic glucose production and fasting hyperglycemia of type I diabetic patients treated with human recombinant ultralente insulin.

OBJECTIVE: To test whether a suppertime injection of human ultralente insulin in patients with type I diabetes would result in a larger inhibition of basal hepatic glucose production (HGP) and improvement in fasting and mean daily plasma glucose levels. RESEARCH DESIGN AND METHODS: We studied 16 type I diabetic patients (41 +/- 4 years of age; body mass index [BMI] = 23.3 +/- 0.3 kg/m2; diabetes duration > 3 years) with a crossover protocol of therapy with an intermediate and ultralente insulin. All patients were already treated with three injections per day of regular insulin in addition to intermediate-acting (NPH) insulin at suppertime. After a 14-day run-in period, patients were randomly assigned to treatment with equivalent doses (10.8 +/- 0.8 U, at 1900) of intermediate (Humulin I) or ultralente (Humulin U) insulin. After 1 month of treatment, patients were crossed over. No change of the insulin dosage was performed during the study period. Basal HGP was measured by D-(6,6-2H2)-glucose infusion. Plasma glucose concentration was measured in the fasting state and monitored during the day. RESULTS: Before starting the study period, fasting plasma glucose was 13.4 +/- 1.1 mM and plasma free-insulin was 48.0 +/- 4.8 pM. Daily plasma glucose concentration averaged 10.3 +/- 0.3 mM and the area under the curve (AUC) was 1.41 +/- 0.05 mol/14 h. NPH insulin, given at suppertime for a month, did not induce significant changes in fasting plasma insulin (40.2 +/- 4.8 pM), glucose concentration (14.0 +/- 0.9 mM) or HGP (20.2 +/- 2.2 mumol.kg-1.min-1). Accordingly, no change occurred in the average daily plasma glucose (10.3 +/- 0.3 mM) or AUC (1.41 +/- 0.9 mol/14 h). Glycated hemoglobin also was not affected (8.2 +/- 0.4 vs. 8.2 +/- 0.3%). On the contrary, a 4-week treatment with ultralente insulin, also given at suppertime, was associated with a decline in the basal HGP (16.0 +/- 1.3 mumol.kg-1.min-1), fasting (11.3 +/- 0.9 mM) and average daily (9.4 +/- 0.3 mM) plasma glucose concentrations, and AUC (1.29 +/- 0.07 mol/14 h) of plasma glucose level (all P < 0.05). Glycated hemoglobin was reduced (7.9 +/- 0.4%). In each condition, fasting plasma glucose concentration was correlated with the average daily plasma glucose level (basal = 0.78; intermediate = 0.89; ultralente = 0.62; all P < 0.05), which suggests that ultralente insulin likely induces the improvements of metabolic control through reducing fasting plasma glucose. CONCLUSIONS: Our results suggest that treating type I diabetic patients with ultralente insulin at suppertime provides a better modulation of basal HGP so that lower fasting plasma glucose levels are ensured. The reduction of fasting hyperglycemia is likely to affect positively daily plasma glucose control.

Adult↗
PubMed1994

[Nuclear DNA in neoplastic pathology of the thyroid gland].

We have analysed the nuclear DNA content in a series of 33 thyroid tumours (18 carcinomas and 15 adenomas) and, for comparison, in 189 nodular strumas and 17 tissue samples of normal thyroids, calculating cell cycle parameters and presence of aneuploid DNA. Cell suspensions were prepared for each of three tissue fragments taken for different areas of the surgical specimens. Cell subpopulations with aneuploid DNA content were present in 39% of carcinomas, 27% of adenomas, 20% of strumas, but were absent in the samples from normal thyroids. The presence of hyperdiploid DNA was much more frequent than that of hypodiploid DNA in all pathologic tissues. The mean proliferation index was 14.1 in the carcinomas, 6.6 in the adenomas, 7.1 in the strumas and 6.1 in normal thyroid tissues. The percent of histograms with a coefficient of variation of the G0-G1 peak greater than 5 was highest in the carcinomas (26%). The significance and implications of the reported data are discussed for the interpretation of thyroid neoplastic pathologies.

Adenocarcinoma↗
PubMed1994

[The role of ergometric testing in the clinical evaluation of arrhythmia].

Ergometric stress testing seems useful in the identification of some supraventricular and ventricular arrhythmias induced by exercise, but poorly indicative for the purpose of prognosis, because the risk of sudden death seems to be linked to the extent of coronary artery disease or left ventricular failure. Ergometric stress testing, with ambulatory ECG, have an important role in the evaluation of the effects of antiarrhythmic drugs. This stress testing, favouring the importance of the efficacy of therapy, of probably worsening of arrhythmia, of congestive heart failure and/or conduction abnormalities, allows a more accurate prescription of physical activity and antiarrhythmic drugs.

Anti-Arrhythmia Agents↗
PubMed1993

Deafferentation induces early and delayed differential changes in the pattern of expression of the various guanine nucleotide binding protein mRNAs in rat striatum.

A polymerase chain reaction-derived method was used to identify and quantitate the relative abundance of the different mRNAs encoding various isoforms of the guanine nucleotide regulatory protein Gs, Gi, and Go alpha subunits in the striata of rats unilaterally injected with 6-hydroxydopamine in the substantia nigra. Thirty days after the lesion, the mRNA levels of the G(o) and of the Gi 1 alpha subunits were increased by about 2-3 times, those of the Gi 3 decreased by about 60% and those of Gi 2 and Gs unmodified. The pattern of expression of the G(o) alpha subunits mRNA changed in a time-dependent fashion, being significant 20 days after the lesion. The decrease in Gi 3 alpha subunit mRNA levels was maximum 10 days after the lesion and tended to be reduced in magnitude with time while the changes in Gi 1 alpha subunit mRNA showed a byphasic behaviour being reduced at 10 days and increased at 30 days after the lesion. These data suggest that the expression of the various G protein alpha subunits in the striatum are continuously regulated by factors originating from afferent neurons and surrounding cells.

Animals↗
PubMed1993

A Tau antisense oligonucleotide decreases neurone sensitivity to excitotoxic injury.

Short-term exposure of primary cultures of cerebellar granule cells from neonatal rat brain to high concentrations of glutamate results in neuronal degeneration. We found that glutamate, before causing neuronal degeneration, induced a significant increase of Tau protein immunostaining. Time-course experiments revealed the increase ot Tau immunoreactivity to be maximal 2 h after the glutamate pulse. To investigate the possible role of newly synthesized Tau protein in the neurotoxic process activated by glutamate, cerebellar granule cells were preincubated with a specific Tau antisense oligonucleotide. This treatment resulted in (i) an inhibition of the glutamate-induced increase of Tau immunoreactivity and (ii) a decrease in the sensitivity of the neurones to neurotoxic concentrations of glutamate. These data indicate that new synthesis of the cytoskeleton-associated Tau protein is a crucial step in the cascade of events promoted by glutamate and leading to neurodegeneration.

Animals↗
PubMed1993

Effects of different plasma glucose concentrations on lipolytic and ketogenic responsiveness to epinephrine in type I (insulin-dependent) diabetic subjects.

The effects of two different plasma glucose concentrations (5 and 10 mmol/L) on lipolysis and ketogenesis during baseline and in response to epinephrine infusion were evaluated in insulin-dependent diabetic patients. Each insulin-dependent diabetic subject was studied during euglycemia, hyperglycemia with hypoinsulinemia, and hyperglycemia with hyperinsulinemia. Total ketone body (TKB) concentrations were significantly higher in hyperglycemic-hypoinsulinemic diabetics than in hyperglycemic-hyperinsulinemic and normoglycemic diabetics. Hyperglycemic-hyperinsulinemics had higher TKB concentrations than euglycemic diabetics. During epinephrine infusion, the ketone body rate of appearance and concentration significantly increased in all groups. Plasma FFA concentrations were significantly higher in hyperglycemic-hypoinsulinemic diabetics than in the other groups. During epinephrine infusion, the plasma FFA rate of appearance and concentration significantly increased in all groups. The apparent fraction of FFA converted to ketones was increased by epinephrine in all groups, except in hyperglycemic-hyperinsulinemic diabetics. In conclusion, this study demonstrates that although insulin alone decreases FFA and TKB concentrations, it does not affect the fraction of FFA converted to ketones. If hyperinsulinemia is superimposed on hyperglycemia, there is both a reduction of ketogenesis capacity, compared to hyperglycemia alone, and a decrease in the apparent fraction of FFA converted to ketone bodies.

Adult↗
PubMed1993

Alcohol intake impairs glucose counterregulation during acute insulin-induced hypoglycemia in IDDM patients. Evidence for a critical role of free fatty acids.

In this study, we assessed the effects of alcohol intake on glucose counterregulation in response to acute insulin-induced hypoglycemia in IDDM patients and in normal control subjects. Nine euglycemic IDDM patients and 9 normal control subjects were studied. After a baseline period, insulin (0.15 U/kg) was administered subcutaneously to induce hypoglycemia. Each IDDM patient was studied 3 times. In the first study, alcohol was orally administered as wine. In the second (control) study, water was administered instead of wine. In the third study, wine was given; however, a continuous infusion of heparin plus intralipid was administered to prevent the fall in plasma free fatty acid. Normal control subjects underwent only the alcohol and the control studies. In IDDM patients alcohol intake impairs, whereas in normal subjects it supports glucose counterregulation. Alcohol intake is associated with normal catecholamine responses in both IDDM diabetic patients and normal subjects. In both IDDM patients and normal subjects, hepatic glucose production in the recovery phase of the alcohol study was normal. Plasma glucose rate of disappearance was significantly increased by alcohol intake in IDDM (13.72 +/- 0.82 vs. 11.84 +/- 0.53 mumol.kg-1 x min-1; P < 0.05). Alcohol intake in both normal subjects and IDDM patients decreased plasma free fatty acid (267 +/- 22 vs. 156 +/- 20 microM; P < 0.01 and 356 +/- 29 vs. 96 +/- 12 microM; P < 0.01). We hypothesized that in IDDM patients, deficient glucose recovery during alcohol intake is the result of the ability of alcohol to depress lipolysis.

Acute Disease↗
PubMed1992

The effects of different plasma insulin concentrations on lipolytic and ketogenic responses to epinephrine in normal and type 1 (insulin-dependent) diabetic humans.

This study was performed to verify: (1) the ability of different insulin concentrations to restrict the lipolytic and ketogenic responses to exogenous epinephrine administration; (2) whether the ability of insulin to suppress the lipolytic and ketogenic responses during epinephrine administration is impaired in Type 1 (insulin-dependent) diabetic patients. Each subject was infused on separate occasions with insulin at rates of 0.2, 0.4, and 0.8 mU.kg-1.min-1 while normoglycaemic. To avoid indirect adrenergic effects on endocrine pancreas secretions, the so-called "islet clamp" technique was used. Rates of appearance of palmitic acid, acetoacetate, and 3-hydroxybutyrate were simultaneously measured with an infusion of 13C-labelled homologous tracers. After a baseline observation period epinephrine was exogenously administered at a rate of 16 ng.kg-1.min-1. At low insulin levels (20 microU/ml) the lipolytic response of comparable magnitude was detected in normal and Type 1 diabetic patients. However, the ketogenic response was significantly higher in Type 1 diabetic patients. During epinephrine administration, similar plasma glucose increments were observed in the two groups (from 4.74 +/- 0.53 to 7.16 +/- 0.77 mmol/l (p less than 0.05) in Type 1 diabetic patients and from 4.94 +/- 0.20 to 7.11 +/- 0.38 mmol/l (p less than 0.05) in normal subjects, respectively). At intermediate insulin levels (35 microU/ml) no significant differences were found between Type 1 diabetic patients and normal subjects, whereas plasma glucose levels rose from 4.98 +/- 0.30 to 6.27 +/- 0.66 mmol/l (p less than 0.05) in Type 1 diabetic patients, and from 5.05 +/- 0.13 to 6.61 +/- 0.22 mmol/l (p less than 0.05) in normal subjects. At high insulin levels (70 microU/ml) the lipolytic response was detectable only in Type 1 diabetic patients; the ketogenic response was reduced in both groups. During the third clamp, a significant rise in plasma glucose concentration during epinephrine infusion was observed in both groups. In conclusion this study shows that at low insulin levels Type 1 diabetic patients show an increased ketogenic response to epinephrine, despite their normal nonesterified fatty acid response. Instead, high insulin levels are able to restrict the ketogenic response to epinephrine in both normal and Type 1 diabetic subjects, although there is a still detectable lipolytic response in the latter. In the presence of plasma free insulin levels that completely restrict the ketogenic response in the same group, there is still a distinct glycaemic response. Plasma insulin levels in Type 1 diabetic patients are a major determinant of the metabolic response to epinephrine.

Acetoacetates↗
PubMed1992

Rat pituitary cells selectively express mRNA encoding the short isoform of the y2 GABAA receptor subunit.

The GABAA receptor belongs to the ligand-gated ion channel receptor superfamily and appears to be composed of from 4 to 5 subunits which interact with each other. Molecular cloning of cDNAs encoding the different subunits of the GABAA receptor has revealed an unexpected heterogeneity which includes at least 4 homologous classes of subunits: these classes, designated as alpha, beta, gamma, and delta contain multiple variants. We have measured the steady-state levels of mRNAs encoding different (alpha 1, alpha 4, beta 1, beta 2, beta 3, gamma 2 long, gamma 2 short and delta) GABAA receptor subunits in the rat anterior pituitary and cerebellum using a polymerase chain reaction (PCR)-derived method. We found that pituitary cells express mRNAs encoding the alpha 1, beta 1 and beta 3 GABAA receptor subunits whereas the transcripts for alpha 4, beta 2 and delta were undetectable. We also found that pituitary cells selectively express the short isoform of the gamma 2 subunit mRNA. These data indicate that the expression of the various GABAA receptor subunits is cell-specific and support the concept that the diversity in function and pharmacology of the GABAA receptor is based on the ability of cells to specify the expression of selective GABAA receptor subunits.

Animals↗